The center of Berlin is at present the largest construction site in Europe. Under enormous time pressure a vast number of organizations and construction companies are working together to create an entire new district in the center of the city. How can this be done in view of the fact that there is no one single organization to coordinate these activities? What role does science play here? The present paper is an analysis of a single case: the 'invention' of a legal argument used by the German railway company Deutsche Bahn AG in the context of invitations to tender for construction work on the Tiergarten tunnel. The author accompanies the juristic argument from its initial conception to its ultimate application in the dispute around Deutsche Bahn invitation practices. His underlying hypothesis is that the implementation of scientific knowledge can be described as the institutionalization of a boundary object. The author further assumes that through a continuous linking of representations and practices boundary objects develop from singular, prototypical objects to generalized, universally applicable objects. In this view, representations ensure that objects will have legitimacy and authority, so that they will have selective advantages over their competitors. Application in practice, on the other hand, predicate the object with those features that are necessary for it to become generalizable. The paper concludes with a discussion of the implications of this model for the sociology of sciences.